In this example, 2001 and Mountain Bikes are in bold text since they represent subtotals whereas the individual mountain bike models are in regular text since they are at the lowest level of detail.

• 在这个例子中，因为2001和山地自行车后面显示小计的结果，所以这里以粗体字体显示，而山地自行车的款式则以正常的字体显示，因为它们在明细数据中等级最低。